MEXICO CITY – Three police officers and a civilian died in a shootout that started during an inspection at a prison in Ciudad Victoria, the capital of the northeastern Mexican state of Tamaulipas, state security officials told EFE, adding that six people were wounded in the incident.

Officials are trying to determine if the people wounded in the shootout on Tuesday are law enforcement agents or inmates, Tamaulipas Public Safety Secretariat spokesman Luis Alberto Rodriguez said.

The fourth person killed in the shootout was a prison guard, but officials have not confirmed this, media reports said.

State police officers went to the penitentiary to conduct an inspection after prison officials detected rising tensions in the facility and suspected that banned items had been smuggled in, Rodriguez told EFE by telephone.

The operation, which continued late into Tuesday night, included Federal Police and army units, which cordoned off the prison.

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